In master cylinders where a piston is rapidly moved past a compensator port in response to an input force, a quantity of brake fluid is lost to the brake system by being squirted out into the reservoir. As long as there is fluid in the master cylinder reservoir, the squirting action which takes place during a brake actuation is not detrimental. However, if the fluid in the reservoir somehow is lost, the fluid in the brake system can also be depleted after several brake applications through this squirting action.
In order to retain the fluid in the brake system it has been disclosed by the prior art to place a small reservoir around the compensator port and place fixed baffles along the top of the small reservoir to modify the transmission of fluid from the small reservoir into the supply reservoir. Unfortunately, the fixed baffles also prevent the entry of various pieces of test equipment into the compensator ports which are needed to evaluate the operation of the master cylinder.